Automatic tracking control mechanism for conveyer belts



June 13, 1950 w, BLABER 2,511,194

AUTOMATIC TRACKING CONTROL MECHANISM FOR CONVEYER BELTS Filed May 31,1947 FIG.2.

FIG. 3.

MICHAEL RWBLABER IN VEN TOR WWW ATTORNEYS Patented June 13, 1950 UNITEDSTATES PATENT OFFICE AUTOMATIC TRACKING CONTROL MECHANISM FOR CONVEYERBELTS Application May 31, 1947, Serial No. 751,554 In Great Britain June14, 1946 4 Claims.

This invention relates to an automatic tracking control mechanism for atravelling belt, bend, web or the like (hereinafter referred to as aconveyor belt), i. e. to a mechanism which will counteract wandering ofthe conveyor belt from side to side during running.

This tendency of the belt to wander is well known and many proposalshave been made for overcoming it. One known type of tracking controlmechanism may be broadly defined as comprising an idler roller extendingacross the full width of the belt which it supports and by which it isfrictionally driven, such roller being carried by a pivoted mount andbeing normally aligned with its longitudinal axis at right-angles to thebelt centre line, and means, e. g. a pair of pulleys, each bearingagainst an edge of the belt so that as the latter wanders, the pulleysmove with it and constantly vary the angular relationship between thedriven roller and the belt, such variation being sufficient for theroller to traverse the belt back to its normal path. In one mechanism ofthis type as previously proposed, a rod extended forwardly from thebearing block of the idler roller, i. e. in the direction from which theconveyor belt was travelling, and was formed at its free end with a pairof outwardly extending arms each carrying an edge-engaging pulley.

Such tracking mechanisms form an integral part of the conveyor beltsystem and since they rely solely on the friction between the idlerroller or rollers and the belt for their operation, the latter should,to be fully emcient, pass partially around the rollers.

It is an object of this invention to provide an improved automatictracking control mechanism for a conveyor belt which is a self-containedunit of simple construction that can be applied to one side of anexisting conveyor belt assembly at any desired point of its length andwhich is positive in operation.

According to this invention, an automatic tracking control mechanism fora conveyor belt comprises a pair of rollers or wheels with their axesnormally at right-angles to the centre line of the belt and frictionallygripping between them a margin of the belt so as to be driven thereby,the wheels being rotatably mounted on arms projecting laterally from avertical pivot positioned to one side of the belt, and a pulley directlyconnected to the pivot and engaging an edge of the belt to follow anydeviation of the latter from its correct path, whereupon the line of thebelt is varied to counteract such deviation.

In order that the invention may be more readily understood, one form ofautomatic tracking control mechanism for a conveyor belt constructed inaccordance with the invention will be described, by way of example, withreference tothe accompanying drawing, wherein:

Fig. 1 is a top plan view of an automatic belt tracking control,constructed in accordance with and illustrating a preferred embodimentof my invention;

Fig. 2 is a side elevation thereof, partly in section and with the rodcarrying the belt edgeengaging pulley removed;

Fig. 3 is a top plan view of the mechanism; and

Fig. 4 is a detail view showing themounting of the edge-engaging pulley.

As shown in the drawing, an L-shaped bracket I mounted to one side ofand spaced from a conveyor belt 2 has a channel-section support 4 boltedor otherwise secured to its vertical limb. A square post 5 is mountedbetween the horizontal limbs M, as by means of countersunk screws 6formed with reduced end portions 6a engaging axial bores 5a in the post5, so as tobe capable of pivoting about a vertical axis. The reduced endof an arm 1 passes through a lateral bore near the lower end of thepivot post 5 and is secured to the latter by a nut 8. The free end ofthe arm 1 constitutes a hub for a freely rotatable wheel 9 which bearsagainst the undersurface of a margin of the belt 2. A second arm inextending parallel to arm 1 and carrying a freely rotatable wheel llbearing on the upper face of said belt margin is secured to the pivotpost 5 near its upper end by a nut I2. The arm I0 is in two parts, apart Illa having a reduced portion passing through the post 5 to receivethe nut I2 and a part lllb in the forked end of part Illa to swingvertically about a pivot pin l3. A tension spring 14 is anchored at eachend to a lug l5 bolted to each of the arms 1, Ill and causes the wheels9, H to grip the belt 2, as shown in Fig. 2, so that they will berotated frictionally as the belt 2 is driven.

A bore I6 is formed in the pivot post 5 intermediate and at right-anglesto the arms I, In to receive an end of a cranked rod l1 extending in thedirection from which the belt 2 travels and secured in position by a nut18. The free end of rod I! supports a grooved pulley [9 which is free torevolve about a vertical axis and bears angle which the wheels make withthe centreagainst an edge of the belt 2. Any suitable means may beprovided for mounting the pulley l9 and, as shown in Fig. 3, such meansmay comprise a forked member 20 threaded onto the screwthreaded end ofrod l1 and a pulley-carrying fork 2| mounted in the member 20 by aheaded clamping screw 22'. By this means, the position of the pulley l9may be varied to traverse the belt laterally.

The operation of the tracking control mechanism is as follows:

When the conveyor belt is running correctly", the grooved pulley I9 isin contact therewith and the axes of the wheels 9, H on the upper and:lower arms 1, I extend at right angles to the direction of travel of thebelt 2. Assuming, however, that the belt 2 wanders to the left (asviewed,

in this case immediately follows the movement of the belt due to theshape of the rod l1 and the frictional contact between the pulleysurface and the belt edge so that the post 5 and the wheels 9, ll pivotin the opposite direction to restore the belt to its normal path. Ifdesired, a light spring (not shown) may be provided to set on the rod I!and ensure positive contact" between the pulley l9 and the belt 2'.

If desired, the belt-gripping wheels 9, H may be duplicated on the othermargin of the belt 2 and be controlled from the same edge-engagingpulley I9. If the conveyor belt or the like is of considerable length,it may be desirable to have a plurality of tracking-control mechanismsas above described arranged along the path of the belt, in which casethey may be arranged alternately or in pairs adjacent opposite edges ofhe belt 2.

The sensitivity of the control mechanism is determined by the length ofthe rod- H carrying the grooved pulley l9 and it will be understood thatthe rod I! may be made adjustable in-length in any suitable manner sothat the sensitivity of the mechanism may be-increased or decreased asdesired.

The rod I! may also be hinged intermediate its length so that the pulleyl9 may beset at different positions for belts of different widths, oralternatively, for traversing the belt from side to side into anydesired position.

It will be appreciated that the mechanism hereinbefore described is ofsimple construction,

requiring no complicated external control devices, and is inherentlyautomatic in operation,

becoming efiective immediately uponthe slightest m deviation of the beltfrom the normal path.

I claim:

1. An automatic tracking control mechanism for conveyor belts,comprising a pair of rollers, arms for the rollers normally at rightangles to a center line of a belt, means for frictionally gripping anedge of the belt between the rollers to drive the rollers from the belt,a pivot carrying the roller arms for swinging movement along the beltand a pulley connected to the pivot and engaging an edge of the belt tofollow the latter from its correct path whereupon the angle which thewheels make with the center line of the belt may be varied to counteractsuch deviation, one of the arms for the rollers including a hinge formovement to and from the other arm, and a spring connecting the two armsfor pressing the rollers against opposite sides of the belt.

2. An automatic tracking control mechanism for conveyor belts,comprising a pair of rollers, arms for supporting the rollers normallyat right angles to a center line of a belt, a support, a pivot mountedon the support and carrying the arms and extending transversely to theplane of the belt at one side thereof, at least one arm being hingedlyattached to the post for movement to and from the other arm, means forurging the pivoted arm toward. the fixed arm to cause said rollers tofrictionally grip the belt on opposite sides thereof, a grooved pulleyengaging an edge of the belt at a spaced distance from the rollers, saidgrooved pulley being revolvably carried on an arm anchored. inthe pivot,whereby the turning movement of the pivot in the support may becontrolled by the grooved pulley to vary the angular relation of therollers to the belt.

3. A mechanism according to claim 2 wherein the arm carrying. thegrooved pulley is at least twice as long as the arms carrying therollers.

4. A mechanism according to claim,2 wherein the arm carrying the groovedpulley is positioned on the pivot at substantially right angles to thearms carrying the roller-s whereby said grooved pulley may engage anedge of the belt amaterial distance from the rollers to guide therollers to and from a positionin parallelism with the edge of said belt.

MICHAEL P. W. BLABER.

REFERENCES CITED lhe following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 769,850 Thompson Sept. 13, 19041,360,717 Bossert Nov. 30, 1920 FOREIGN PA'IENTS Number Country Date552,697 Great Britain Apr. 20, 1943

